Darmain and Schweinsteiger all had their medicals over the weekend before the club surprisingly announced the signing of French midfielder, Schniederlin.
Two weeks ago, Koeman rejected United’s offer of £20 million and said that, “Every player has his price and we have experience as a club of selling players”.
Doubts had arisen over Arteta’s future as his old contract was left to expire and Arsene Wenger was supposedly close to bringing in Chilean Copa America victor Arturo Vidal.
Manchester United are poised to make a second bid for Morgan Schneiderlin after Southampton rejected an opening offer of around £20m for the midfielder.